Process of producing high-percentage transparent soaps



'UNITED STATES PATENT OFFICE Paoonss or PRODUCING HIGH-PERCENT- AGE TRANSPARENT soAPs Wilhelm Pape, Benrath-on-the-Rhine, Germany, assignor, by mesne assignments, to Procter & Gamble Company, Ivorydale, Ohio No Drawing. Application August 29, 1932, Serial No. 630,974. In Germany November 13, 1931 4 Claims. (Cl. 8716) Non-transparent soaps will solidify from the which the screw is rotated at a much lower speed hot fluid state to a crystal conglomerate, which than in the production of common toilet soaps. contains more or less soap in colloidal dispersed Finally bars or pieces of the desired size and state. Transparent soaps as usually made are shape are formed from the string of soap.

5 solid, under-cooled solutions to which alcohol, The process may be carried out with any de- 5 glycerine, sugar, crystal soda or similar substances sired fatty mixture of the kind hitherto used for have been added in order to prevent a crystalthe production of transparent soaps. In most lization of the mass during the solidification. cases even the use of glue fats or of castor oil Filled transparent soaps, when produced in this (which is particularly well suited for transparent manner, are allowed to cool slowly and, after soaps) may be dispensed with. proper drying are formed by means of a press The novel process may for instance be carried into bodies of suitable form and size. Soaps of out in the following manner: this kind contain only about 40% of fatty acid, A fatty mixture of suitable composition is saare more or lessstrongly alkaline and are rapidly ponified in the presence of a sufficient amount of used up. On account of their high content of resin, preferably without the addition of any elec- 15 alkali and crystal soda they also irritate the skin. trolytes. The treatment is conducted in such 9.. Moreover, these soaps must be stored for a long manner, that a substantially neutral soap is obtime before they are put upon the market and, tained, in which no perceptible quantity of free on accountv of the filler substances contained alkalies is present and which is highly concentherein, are very ineconomical in use. Such soaps trated, so that the mass, after complete saponi- 20 are also disproportionally expensive and this fication, contains about 64-66% of actual 'soap drawback is chiefly due to the inevitable losses and is usually of a very thick consistency. The of alcohol which occur during their production. fatty substances and the alkali used should, as in It is also possible to produce a high percent the case of known transparent soaps, be very transparent soap without the use of filler and pure. containing about 73-75% fatty acid, but even in Soaps obtained in the manner described above this case it is necessary to use large quantities of without the use of known filler substances will alcohol, which subsequently must be distilled off normally solidify to a Cry non-transparwhereby losses are inevitable. The obtained soap ent mass. If, however, the hot liquid mass not must be stored for a long time, usually for sevonly is cooledto a low degree (for instance in eral months, whereby the costs of manufacture of cooling plate machines) but also is suddenly course are considerably increased. cooled in the form of a thin layer, glass-clear, After thorough and prolonged investigations, transparent strips or slabs are obtained. The r I have now succeeded in developing a process by temperature must be very rapidly reducedto means of which a clear high percent kneaded room temperature, in order to avoid the formatransparent soap, viz: a transparent soap contion of crystals at the usual solidification tem taining a high percentage of saponifled fatty perature. Crystallization is also retarded by acids, may be obtained without filler substances. the presence of the resin soaps. The sudden The novel process consists essentially in saponifycooling is preferably performed on rollers cooled 40 ing a suitably thoroughly pre-purified batch of to a low degree. 40 fatty matter with pre-purifled alkalies in the The soap produced by the method described presence of saponifiable natural resin in amounts above is dried if necessary. The drying should suflicient to retard the crystallization. Preferbe performed in an air current at normal temably neither electrolytes nor the usual additions perature, since crystallization would take place of glycerine, alcohol, sugar, crystal soda or the if the mass were heated. The amount of moislike are used. The hot fluid soap is thereupon, ture or fatty acid which the soap must'contain while in the form of a thin layer, suddenly cooled before it is treated in the plodder depends upon I to room temperature and, it necessary, dried in the composition of the batch of fatty matter the air. When drying, however, care must be used. For normal batches the contents of fatty taken to avoid super-saturation. The glass-clear acid should not greatly exceed 70%, since othersoap obtained is kneaded and, if desired, mixed wise a super-saturated solid solution is obtained with scent' and other additional substances by and crystals are formed in spite of the previous means of cold rollers in a suitable kneading or sudden cooling. The soap is now fed into a plodmixing apparatus, and is thereupon pressed to der having a cooled pressing head. The conveyor a string in a plodder having acooled head and of screw or worm of the plodder is rotated at a 55 speed which is considerably lower than the speed normally used in the manufacture of toilet soaps. If necessary, the number of revolutions of the feed screw is reduced to half the normal number. On account of the colloidal structure of the transparent strips the soap is very tough and dense and the plodder must therefore be operated at a speed which is considerably lower than when producing normal kneaded soap, in order that air entering the plodder with the soap mass may have ample time to escape. If the plodder is run at a too high speed air bubbles will be enclosed in the mass and impair the appearance of the otherwise homogeneous, transparent soap. From the finished transparent string of soap pieces of the desired size and shape are formed in known manner by means of a suitable device.

When the soap mass in the form of a thin layer has been suddenly cooled on cold rollers, the mass is simultaneously dried and, in some cases, the desired degree of dryness is also obtained by this treatment. It will, however, in many cases be necessary to subject the mass to a subsequent drying treatment, and this treatment must be performed with care, since the mass will turn turbid if said treatment is exaggerated. If the soap string leaving the plodder should be turbid, a small amount of water is added to the mass and the mass is once more passed over the cold rollers, whereupon the treatment is continued in the manner described above.

Example 1 A batch of fatty matter consisting of 61 kg. of tallow, 18 kg. of cocoa nut oil, 11 kg. of castor oil and 10 kg. of saponifiable natural resin is, after cautious purification, saponiiled with 45,8 kg. of purified soda lye of 39 B. The transparent, hot, almost neutral soap gel is thereupon applied to cooled rollers in such a manner, that, in the course of few (2-3) seconds, the temperature is reduced from 90-100 C. to about C. The ribbons or plates are scented, kneaded once or twice on cold rollers and are thereupon, while containing about 71% of fatty acids, passed through a slow operating plodder, the head of which is cooled. The string of soap is cut up and pieces of suitable size and shape are formed from the same. The obtained soap is very transparent and is immediately in transportable state. When stored the soap will dry without altering its shape. Finally the soap has a fatty acid content of about 73-75%.

Example 2 A batch of fatty material consisting of 92 kg. of crude palm oil and 8 kg. of saponifiable natural resin is purified, completely saponifled with 42,9 kg. of soda lye of 38 B. and subjected to a further treatment as described above.

The obtained transparent soaps are non-filled, kneaded toilet soaps of high quality and glasslike transparency. On account of their high percentage of fatty acids, usually amounting to 71-75%, they are very economical in use and are not used up as rapidly as the transparent soaps hitherto known. The novel soaps are agreeable to the skin and may be produced at low costs. Other advantages of the novel process reside in the shortening of the time required for producing the soap and in the fact that it is not necessary to store the soap for any length of time. The soaps may therefore be placed on the market immediately after the same have been manuf actured. In contrast to this the heretofore known low-percentage transparent soaps must be stored for a considerable time before the desired high degree of transparency is obtained. The novel soaps may be scented in the same manner as the usual toilet soaps.

I claim:

1. A process of producing transparent kneaded toilet soaps containing a high percentage of fatty acids consisting of saponifying a mixture of fats and saponiilable natural resin with concentrated soda lye not substantially in excess in the substantial absence of an electrolyte, and while the soap is at a temperature of liquefaction suddenly cooling it to a temperature sufficiently low to prevent crystallization, drying the soap under conditions which prevent crystallization, subsequently kneading and plodding while cooling the soap, and then forming the soap into bars.

2. A process of producing transparent kneaded toilet soaps containing a high percentage of fatty acids comprising the steps of saponifying a batch of fatty matter by means of concentrated alkalies not substantially in excess in the absence of an electrolyte and in the presence of saponifiable natural resinin an amount sufficient to retard the formation of crystals, spreading the obtained hot fluid soap in a thin layer, cooling said layer suddenly to normal temperature, kneading the obtained mass on cold rollers, passing the mass through a plodder, and forming pieces of the desired size and shape from the mass delivered from said plodder.

3. A process of producing transparent kneaded toilet soaps containing ahigh percentage of fatty acids comprising the steps of saponifying a batch of fatty matter by means of concentrated alkalies not substantially in excess in the presence of saponifiable natural resin in an amount sufficient to retard the formation of crystals, spreading the obtained hot fluid in a thin layer, cooling said layer suddenly to normal temperature, drying the obtained mass under conditions to prevent a crystallization of same, kneading the obtained mass on cold rollers, passing the mass through a plodder having a cooled head and operating at relatively low speed, and forming pieces of the desired size and shape from the mass delivered from said plodder.

4. As an article of manufacture the product produced by the process of claim 1, consisting of a substantially transparent, kneaded toilet soap bar containing substantially seventy-one per cent to seventy-five per cent of fatty acids and having the original shape that it had when stamped as a bar.

WILHELM PAPE. 

